Was china not a super power in early medi times?

中国在中世纪早期不是超级大国吗?


Today i had an discussion in class about the worlds greatest power over time.And when we riched the period after Rome's fall to the visigoths we disagreed about what was the world top superpower then.
Long story short we decided it was the E.R.E And i couldnt help but wonder why it wasnt China (the teacher didnt have time to answer it).Can somebody please tell me why Byzantium was considered superior to china at that time (5th century to 11th century)?

今天我在课堂上讨论了随着时间的推移世界上最强大的力量。当我们说到在罗马倒台后的那段时间里时,我们对当时的世界顶级超级大国有不同的看法。
长话短说,我们决定当时的超级大国是E.R.E(东罗马/拜占庭帝国),我不禁想知道为什么不是中国(老师没有时间回答)。有人能告诉我为什么拜占庭在当时(5世纪到11世纪)被认为优于中国吗?